Planing boat

ABSTRACT

A hull (5) of a planing boat (1) consists of front and rear hull portions (5a, 5b). A bottom part (2a) of the front hull portion (5a) forms one front planing portion (21a), and a recess (7) is provided so as to extend along the center line of the rear hull portion (5b), two bottom parts (2b&#39;) either of which is positioned on the left or right side of this recess (7) forming two rear planing portions (21b). When the speed of the planing boat (1) is low, it runs with the front and rear planing portions (21a, 21b) completely submerged, and, when the speed of the planing boat (1) is high, it floats and plans on the water surface with the hull (5) supported on three portions, one front planing portion (21a) and two rear planing portions (21b).

TECHNICAL FIELD

This invention relates to a planing boat which skims over the surface ofwater at high speeds.

BACKGROUND ART

Generally, in a single-hull type planing boat, as the speed of the boatincreases, the center of lift shifts too much toward the stern withrespect to the center of gravity, causing a porpoising and a largepitching, making the traveling unstable.

On the other hand, in a 3-point-support type planing boat whose forepartis supported by two planing portions and its afterpart is supported byone planing portion, the center of gravity is located between threefront and rear lifts even when the speed of the boat increases. Thisprevents a porpoising and a large pitching, realizing a stable planingon the surface of water.

In the latter type, however, since the number of planing portions in theforepart of the hull is greater than that in the afterpart, the abilityof making a turn is degraded. Another drawback is that since only oneplaning portion is provided in the afterpart, it is difficult to mounttwo or more engines. Furthermore, there is a limitation in thearrangement of the cabin space.

DISCLOSURE OF THE INVENTION

This invention has been accomplished with a view to overcoming theabovementioned drawbacks. The object of the invention is to provide aplaning boat that can realize a stable high-speed skimming over thesurface of water and which has an improved performance of advancingstraight ahead and making a turn and an improved sea kindliness,compared with the conventional 3-point-support type planing boat.

Another object of the invention is to provide a planing boat which canmount a plurality of engines and has reduced restriction in thearrangement of cabin space.

The planing boat of this invention is characterized in comprising:

a front hull portion ranging from the bow to the mid portion of thehull;

a rear hull portion ranging from the mid portion of the hull to thestern, the rear hull portion being formed with a recess, the recessopening downwardly from the bottom part of the rear hull portion, therecess also opening rearwardly from the stern, the rear hull portionhaving a plurality of bottom parts on the left and right side of therecess;

one front planing portion formed by the bottom part of the front hullportion; and

a plurality of rear planing portions formed by the plurality of bottomparts of the rear hull portion.

The planing boat of this invention with the above construction has thefollowing advantages.

(a) A stable high-speed skimming is achieved. The skeg effect by aplurality of rear planing portions in the rear hull portion improves thecourse keeping performance over the conventional 3-point-support typeglide boat.

(b) The combination of the smooth turning capability of the bow and thekeel effect of the stern assures a good overall turning performance.

(c) The 3-point support ensures a good sea kindliness. At the same time,the skeg effect of the stern also improves the course stability infollowing seas.

(d) Because a plurality of rear planing portions are provided to therear hull portion, a plurality of engines can be mounted.

(e) There is less limitation in arranging the cabin space, compared withthe conventional 3-point-support type planing boat.

In this invention, it is desirable to provide a step to the rear end ofthe front planing portion to reduce the water contact area as much aspossible and therefore the influence of waves.

It is also desired that front fins be provided to each side of the fronthull portion to generate lift for floating the hull.

Further, by providing the lift generating fins to the rear hull portionas well as to each side of the front hull portion, it is possible tofurther reduce the depth of the draft when the boat is running at highspeeds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic views showing the characteristic of asingle-hull type planing boat;

FIGS. 2A and 2B are schematic views showing the characteristic of aconventional 3-point-support type planing boat with two support pointsat the forepart of the hull and one support point at the afterpart;

FIG. 3 is a side view of the planing boat as a first embodiment of theinvention;

FIG. 4 is a bottom view of FIG. 3;

FIG. 5 is a front view of FIG. 3;

FIG. 6 is a back view of FIG. 3;

FIG. 7 is a perspective view showing the state of the planing boat whileit is running at a high speed;

FIG. 8 is a bottom view showing the essential portion of the planingboat as a second embodiment of the invention;

FIG. 9 is a back view of FIG. 8;

FIG. 10 is a bottom view showing essential portions of the planing boatas a third embodiment of the invention;

FIG. 11 is a bottom view showing essential portions of the planing boatas a fourth embodiment of the invention;

FIG. 12 is a front view of FIG. 11;

FIG. 13 is a side view of the planing boat as a fifth embodiment of theinvention;

FIG. 14 is a bottom view of FIG. 13; and

FIG. 15 is a perspective view of FIG. 13.

BEST MODE FOR CARRYING OUT THE INVENTION

In a single-hull type planing boat, as shown in FIGS. 1A and 1B, as thespeed of the boat increases, the center of lift L of the single-hulledplaning boat 1' generally shifts too much toward the afterpart of thehull with respect to the center of gravity G. This results in aporpoising and a large pitching, making the traveling unstable.

On the other hand, as shown in FIGS. 2A and 2B, in a 3-point-supporttype planing boat 1", which has its forepart supported by two planingportions 21a and its afterpart by one planing portion 21b, the center ofgravity G is located between three front and rear lifts L even when thespeed of the boat increases. This prevents porpoising and largepitching, realizing a stable planing on the surface of the water.

In the latter type, however, since the number of planing portions in theforepart of the hull is greater than that in the afterpart, the abilityof making a turn is degraded. Another drawback is that since only oneplaning portion 21b is provided in the afterpart, it is difficult tomount two or more engines. Furthermore, there is a restriction in thearrangement of the cabin space.

A planing boat 1 of this invention has a special shape as shown in FIGS.3 through 6. The planing boat 1 looks like a single-hull type at firstsight but in reality it exhibits the contour of a so-called3-point-support type with three support points-obe at the forepart andtwo at the afterpart-when it skims over the surface at high speeds,about 20 to 40 knots.

As shown in FIG. 3, a hull 5 of the planing boat 1 consists of a fronthull portion 5a ranging from the bow 3 to the mid portion 20 and a rearhull portion 5b ranging from the mid portion 20 to the stern 4.

As shown in FIG. 4, a bottom part 2a of the front hull portion 5a formsa front planing portion 21a. A bottom part 2b of the rear hull portion5b is formed with a recess 7. Two bottom parts 2b' on each side of therecess 7 form two rear planing portions 21b. The recess 7 has an opening13 which opens downwardly from the bottom part 2b and an opening 14which opens rearwardly from the stern 4.

If we let L₀ stand for the overall length of the planing boat 1, it isdesirable to set the width L₁ and the height L₂ in the range of 0.25 L₀to 0.50 L₀. The length L₃ of the front hull portion 5a is preferably setin the range of 0.30 L₀ to 0.70 L₀, or, more desirably, between 0.30 L₀and 0.60 L₀.

The hull 5, as shown in FIG. 3, has a step 6 at the rear end of thefront planing portion 21a to minimize the effects of waves. The step 6is formed by providing the recess 7 to the bottom part 2b of the rearhull portion 5b. The height L₄ of the step 6 is preferably set in therange of 0.02 L₀ to 0.08 L₀.

The bottom parts 2b' of the rear hull portion 5b are provided with ahollowed-out portion 6a at the front end thereof. The length of theuppermost part of the hollowed-out portion 6a is preferably set in therange of 0.02 L₀ to 0.25 L₀. The rear ends of the bottom parts 2b' ofthe rear hull portion 5b are located L₆ above the base line B.L. Thedistance L₆ is desirably set in the range of 0 to 0.05 L₀.

The ceiling portion 8 of the recess 7, as shown in FIG. 3, is inclinedupwardly rearwardly toward the stern 4. The width L₇ of the recess 7 isalmost equal to that of the bottom part 2a of the front hull portion 5a.The width L₇ of the recess 7 is preferably set in the range of 0.06 L₀to 0.15 L₀.

As shown in FIG. 4, a front fin 9 for generating a lift is provided toeach side of the front hull portion 5a at the rear end.

Each of the front fins 9, as shown in FIG. 5, consists of an inclinedportion 9a fixed to the lower end of a first hull side 10 of the fronthull portion 5a, a support portion 9c fixed to the upper end of a thirdhull side 12, and an intermediate portion 9b connecting these twoportions 9a and 9c. The angle θ between the horizontal plane H and theinclined portion 9a of the fin 9 is preferably in the range between -10°and 45°. The width L₈ of the front fin 9 is preferably in the rangebetween 0.025 L₀ and 0.30 L₀.

The first hull side 10 and the second hull side 11 of the front hullportion 5a have almost no upward expansion, as shown in FIG. 5, to avoidundesirable influence of waves.

In the figure, reference numeral 15 denotes a first wave damper ormoderator provided to the lower end of the first hull side 10; 16 asecond wave moderator provided to the lower end of the second hull side11; 17 a cabin; 18 a hull side of the rear hull portion 5b; and 23 apropeller, two propellers being mounted at the rear hull portion 5b.

When the planing boat 1 of the above construction travels on the watersurface at a low speed, the front planing portion 21a and the two rearplaning portions 21b move forward fully submerged. As the speedincreases, the floatage of the hull 5 increases and the lift by thefront fins 9 also increases substantially, floating the hull 5. At amaximum speed, the boat travels with the hull 5 supported at threepoints, one front planing portion 21a and two rear planing portions 21b,as shown in FIG. 7. In the figure, G represents the center of gravityand L the lift.

To make the draft of the stern shallow during running, a rear fin 19 maybe mounted to the rear end of the rear hull portion 5b, straddling therecess 7, as shown in FIGS. 8 and 9. The width L₉ of the rear fin 19 ispreferably be set in the range between 0.025 L₀ and 0.30 L₀.

The rear fin 19 may be formed as a pair of cantilever fins 19a, 19a, asshown in FIG. 10. The front fin 9 may be formed of only the inclinedportion 9a as shown in FIGS. 11 and 12.

FIGS. 13 to 15 show a further embodiment of the planing boat accordingto this invention, whose construction is basically the same as that ofthe planing boat 1 of the first embodiment.

This embodiment differs from the first embodiment in that the width ofthe front hull portion 5a is not made excessively narrow and the boat'scontour is made smooth and continuous over the entire length in order toprovide as large a cabin space 25 as possible.

As shown in FIG. 13, the hull 50 of the planing boat 1a consists of afront hull portion 5a ranging from the bow 3 to the mid portion 20 ofthe hull and a rear hull portion 5b ranging from the mid portion 20 tothe stern 4.

In FIG. 14, a bottom part 2a of the front hull portion 5a forms a frontplaning portion 21a. The rear hull portion 5b is formed at its bottompart 2b with a recess 7. Two bottom parts 2b' on each side of the recess7 form two rear planing portions 21b. The recess 7 has an opening 13which opens downwardly from the bottom part 2b and an opening 14 whichopens rearwardly from the stern 4.

If we let L₀ stand for the overall length of the planing boat 1a, it isdesirable to set the width L₁ and the height L₂ in the range of 0.25 L₀to 0.50 L₀. The length L₃ of the front hull portion 5a is preferably setin the range of 0.30 L₀ to 0.70 L₀ or, more desirably, between 0.30 L₀and 0.60 L₀.

The hull 50, as shown in FIG. 13, has a step 6 at the rear end of thefront planing portion 21a to minimize the effects of waves. The step 6is formed by providing the recess 7 to the bottom part 2b of the rearhull portion 5b. The height L₄ of the step 6 is preferably set in therange of 0.02 L₀ to 0.08 L₀.

The rear ends of the bottom parts 2b' of the rear hull portion 5b arelocated a distance L₆ above the base line B.L. The distance L₆ isdesirably set in the range of 0 to 0.05 L₀.

The ceiling portion 8 of the recess 7, as shown in FIG. 13, is inclinedupwardly rearwardly toward the stern 4. The width L₇ of the recess 7 isslightly narrower than the width of the bottom part 2a of the front hullportion 5a. The width L₇ of the recess 7 is preferably set in the rangeof 0.06 L₀ to 0.15 L₀.

A first hull side 26 and a second hull side 27 are formed smooth andcontinuous over the entire length from the bow 3 to the stern 4 so thata wide cabin space 25 can be provided under the deck 24.

Reference numeral 28 represents a third hull side provided between thefirst hull side 26 and the second hull side 27; 29 a first wavemoderator provided to the lower end of the first hull side 26; 30 asecond wave moderator provided to the lower end of the second hull side27; 17 a cabin; and 23 a propeller, two propellers being mounted at therear hull portion 5b.

In FIGS. 1A, 2A, 7 and 13, W.L. represents a static water surface.

We claim:
 1. A planing boat comprising:a front hull portion ranging fromthe bow to the mid portion of the hull, wherein said front hull portionhas front fins on each side to generate lift, and wherein said frontfins comprise inclined portions disposed at a lower end of said fronthull portion, support portions disposed at an upper end of said fronthull portion, and intermediate portions disposed between and connectingsaid inclined portions and said support portions; a rear hull portionranging from the mid portion of the hull to the stern, the rear hullportion being formed with a recess, the recess opening downwardly fromthe bottom part of the rear hull portion, the recess also openingrearwardly from the stern, the rear hull portion having a plurality ofbottom parts on the left and right side of the recess, said recesscomprising a ceiling portion inclined upwardly and rearwardly towardsaid stern; a single front planing portion formed by the bottom part ofthe front hull portion substantially in the center thereof; and aplurality of rear planing portions formed by the plurality of bottomparts of the rear hull portion.